Few family reunions unfold totally free of bitter aftertastes, and Sweet and Sad is no exception. Richard Nelson’s new play at The Public Theater once again brings together members of the Apple clan, whom Nelson introduced in That Hopey Changey Thing last year, and who have not all congregated in one room since that play’s events unfolded. The Apples are as alive and lively now as they were then, and are embodied by the same spectacular cast. But each of them, and the play itself (which Nelson has also directed), are more at odds with their surroundings now, and are erring on just this side of stale. As any grocer will tell you, an apple past its prime isn’t worth sampling — and Nelson’s bushel is getting close to its expiration date.

The problem, such as it is, stems from the play’s flash point or, if you prefer, gimmick of taking place in more or less real time. Just as the first chapter in the Apple saga took place on Election Night 2010, and the production opened itself to the press (who were also in attendance) that same evening, this one is rooted on the occasion of a brunch on the tenth anniversary of the September 11, 2001 terror attacks — with, yes, that performance being the one I saw. The previous play’s spinning a straightforward, barely plotted tale of a group of New York leftists forced to reconsider the boundaries of their liberal thinking was so poignant and pointed, and anchored to its moment, that you couldn’t help but be at least somewhat impressed. For Sweet and Sad, however, the attacks are for the most part background information.

The distinction is a minute but vital one, as it constitutes the difference between a play that Nelson extracts from the present and one that merely takes place there. The Apples’ concerns are now much more grounded and, well, much more boring, evincing signs of careful construction rather than spontaneous life. Everyone relates uncomfortably closely to the attacks: Richard (Jay O. Sanders), a high-powered lawyer for the State whose life regularly intersected with the Financial District; Barbara (Maryann Plunkett), a teacher struggling with what to tell her students about what happened and how they should react; Jane (J. Smith-Cameron), who’s trying to make sense of the attacks’ effects on the American audience; the uncle Benjamin (Jon DeVries) who’s suffering from amnesia, but planning to read a poem at a memorial that night; and Marian (Laila Robins), who’s working to come to terms with the suicide of her daughter and her husband’s callous reaction to that loss. Tim Andrews (Shuler Hensley), Jane’s boyfriend, is also in attendance, as always a first-person chronicler of the human condition.

There’s little for any of them to do in terms of narrative except tell their stories, share their pain and prescriptions, and move on — and the primary thing that prevents the show from becoming deeply static is the boundless talent of the acting company. Seeing Robins’s Marian try — and so often fail — to maintain her composure whenever the subject of children is raised is heartbreaking. Plunkett movingly grows from apolitical to genuinely concerned, as she begins questioning whether the families of 9/11 victims deserve government money. Smith-Cameron’s businesslike rapport with others, the at-odds camaraderie that Sanders and Hensley both display in varying quantities, and DeVries’s gentle disconnection from the places and people that surround Benjamin complete the picture of a family that covers every inch of the emotional spectrum as it relates to loss.

But the patness of it all does wear after a while, with certain anecdotes (one about Revolutionary War general Lafayette, another about theatre manager David Belasco, one a slice of Benjamin’s own forgotten history) too-emphatic ways of communicating certain ideas and, worse, too much of the action feeling schematic rather than organic. This play’s structure closely mimics That Hopey Changey Thing’s, with the same early surges of blackouts dividing a meal into meaningful moments, the same boundary-breaking heart-to-hearts following the final course, and the same climax in an artistic performance that unites everyone in its unassuming virtuosity. There are few substantive discussions of American foreign policy over the last decade, no real questions raised about right or wrong, no searing recollections of being in or near the World Trade Center or vicious disagreements about what, if anything, all of it meant. A couple of second-hand stories and abandoned datebooks, which become coffee-time conversation pieces, do all the heavy lifting

Is there anything wrong with this? Of course not, especially if (as seems to be the case) Nelson is becoming more interested in dissecting the Apples’ trials and tribulations than in how they relate to society around them. But then he either needs to flesh out most of the characters much more (only Marian receives the full treatment this time around) or pump up the topicality so it feels integral to the action rather than incidental. His quiet yet powerful direction is wonderfully paced, and presents the script in the best imaginable light. Unfortunately, the Apples aren’t rich enough as drawn here to support a play without the current-events hook, and what they’re gathering to commemorate does not play as compelling enough to them to justify its inclusion. If there’s an ideal middle ground here, Nelson hasn’t yet found it.

It’s possible that Nelson is building up to something, and that this play’s exploration of these six people’s ordinary lives will take on greater significance in future works. (Nelson states in a script note he currently expects this project to encompass four plays, but offers no hint as to what subsequent ones will be about.) If that’s what he has in mind, this play could be a vital middle step in the Apples’ evolution, the one where everyone grows up in the shadow of an atrocity that stunted America’s growth. But as it stands, thoughtful and uneven, and intriguing but incomplete, Sweet and Sad lives up too readily to its Whitman-inspired title: incredible promise that stops short of the sublime heights its premise proposes.